噪声中EP信号的提取算法及研究进展

诱发电位的提取是脑电信号处理领域的前沿课题近年来 ,通过少次甚至单次试验提取诱发电位已经成为研究的主流。本文对近年来提取诱发电位的信号处理方法进行了简要的回顾 ,并分别从小波变换、神经网络、高阶累积量、独立分量分析等四个方面对算法进行了介绍     

丙戊酸钠静脉滴注治疗偏头痛持续状态

目的评估丙戊酸钠治疗偏头痛持续状态的有效性和安全性。方法我们前瞻性地用静脉滴注丙戊酸钠来治疗偏头痛持续状态,然后比较患者治疗前与出院时视觉模拟评分(VAS)。并比较各种因素(一般情况,累计的丙戊酸钠剂量,合并用药)与治疗之间的关系。结果首次治疗中,26次(74.3%)治疗时患者VAS评分较治疗前减少50%或50%以上。所有治疗中,37次(82.2%)治疗使患者VAS评分较治疗前减少50%或50%以上。患者的性别与治疗反应无关。所有治疗中,合并用药(强痛定,索密通,散粒痛和达宁)和治疗时间与治疗反应呈负相关。仅3例(8.6%)出现短暂性眩晕。结论丙戊酸钠静滴是快速,有效和安全的止痛治疗。它对偏头痛持续状态有效。     

Monocular contribution to the peak time of the binocular pattern visual evoked potential

The contribution of each monocular pathway to the timing of the binocular pattern visual evoked potential was assessed in situations where a significant interocular timing discrepancy was observed. Monocular and binocular pattern visual evoked potentials to 0.5° checks were recorded from normal subjects, normal subjects in whom one eye was blurred, patients with monocular amblyopia, and patients with resolved unilateral optic neuritis. Normal subjects showed facilitation, while suppression was evidenced in subjects with monocular blurring. In patients with amblyopia, the affected pathway had no effect on binocular pattern visual evoked potential latency, suggesting that the amblyopic eye was suppressed. In contrast, all patients with optic neuritis showed binocular averaging. Our results show that different forms of binocular interaction are evidenced in normal subjects, in amblyopia and in optic neuritis, and suggest that a comparative analysis of monocular and binocular pattern visual evoked potential peak times brings valuable information to the clinical evaluation that could be used to distinguish disease processes further.Abbreviation BPVEP binocular pattern visual evoked potential     

BP神经网络及其在药学研究中的应用

BP神经网络是目前应用最广泛的人工神经网络模型，本文详细阐述了BP神经网络的原理和特点，并论述了其在药学研究中的应用。     

Does work with visual display units impair visual activities after work?

It is well established that visual display unit (VDU) operators complain of visual fatigue and visual stress during after-work hours. The present study was divided into two parts. In the first part, standard eye examinations were performed on a group of VDU workers (n = 32) and a control group (n = 15); those subjects who were found to have correct vision (n = 16 and 13, respectively) participated in the second part. The eye examinations revealed that on the average, the VDU workers suffered more than twice as many visual impairments as the controls. In those with correct vision, the near point of accommodation was measured at the beginning of the workday at the start of the week, and at the end of the workday, four days later. In the VDU group, the decrease in accommodation was uniformally distributed between zero and 1.0 diopter, whereas among the non-VDU workers, 77% of the decrease was between zero and 0.25 diopter. The dynamic range of accommodation in the VDU workers on the second examination was smaller than on the first. We conclude that some of the visual stress and visual fatigue that developed at work hindered visual activities after work.     

Platelet aggregation,disc haemorrhage and progressive loss of visual fields in glaucoma

Platelet aggregationin vitro, deterioration of visual field defects (VFD) and the prevalence of disc haemorrhages (DH) were assessed in 49 patients with primary open angle glaucoma (POAG) and compared with the findings for 67 individuals with suspected glaucoma (GS) in a seven-year follow-up study (range 5.8 to 8.2 years). The percentage patients with spontaneous platelet aggregation (SPA) was higher for POAG patients with visual field deterioration (60%) than both POAG patients without progressive loss of visual fields (12.5%; P<0.005) and those with suspected glaucoma (22.4%; P<0.005). The occurrence of DH was higher among POAG patients with progressive loss of visual field (28%) compared to the GS group (8.4%; P<0.025) and the group of patients consisting of POAG patients without deterioration of VFD and GS (9.9%; P<0.05). DH also occurred more often in patients with low tension glaucoma (41.6%) than in the remaining POAG patients (13.5%; P<0.05). No relation between the patients with SPA and the patients with DH was observed.Abbreviations NPB normal platelet behavior - SPA spontaneous platelet aggregation - DH disc haemorrhage     

Endophthalmitis at the Bristol Eye Hospital: an 11-year review of 47 patients

We reviewed data from 47 patients who were treated for endophthalmitis at our hospital during the 11-year period 1980-90. The most common clinical features were hypopyon (75%), diminished vision (72%), ocular pain (68%), discharge (57%), corneal oedema (51%), conjunctival injection (49%), abnormal red reflex (34%), corneal ulcer (32%) and corneal perforation (6%). A total of 54 isolates were obtained from 41 (87%) of the 47 patients. Gram-positive bacteria were more common (72%), than Gram-negative organisms (22%). Two cases were due to fungi, and herpes simplex virus was isolated from one case. The two most common Gram-positive organisms were coagulase-negative staphylococci (25%), and Staphylococcus aureus (11%), while Pseudomonas aeruginosa predominated among the Gram-negative bacteria isolated (15%). Mixed bacterial species were obtained from 29% of the infected patients, including one from whom Vibrio fluvialis was isolated. Predisposing factors included ocular surgery (60%)--mostly for cataract extraction (47%), penetrating trauma (15%) and periocular (15%) or systemic (11%) infections. All patients received antibiotics (generally chloramphenicol and/or a beta-lactamase-stable penicillin plus an aminoglycoside) prior to culture, when treatment was adjusted according to specific aetiological agents. Seventy-nine per cent of patients received topical or systemic steroids. Vitrectomy (diagnostic and therapeutic) was performed on 21% of patients. Sixty-three per cent of culture-positive patients lost vision (no perception of light) in the affected eye, compared to 17% of culture-negative cases (P < 0.05 Fisher exact test). Similarly, a better visual outcome (acuity of 6/12 or better) was associated with coagulase-negative staphylococcal infection than with streptococcal or fungal infections.(ABSTRACT TRUNCATED AT 250 WORDS)     

关于口腔医学多媒体及网络教学实验效果的分析

采用比较研究的方法进行了口腔医学多媒体及网络教学实验，旨在观察比较网络教学环境、多媒体课件演示以及传统教师讲授等多种教学方式的教学效果，分析传统教学与网络教学模式下的教学环节、教学效果以及存在问题，对课件进行总体评价，对影响因素进行分析，对多媒体及网络教学模式作一初步的实践和探索。     

闪光视觉诱发电位监测甘露醇降颅压效果的临床研究

目的利用闪光视觉诱发电位监测颅内高压患者颅压水平,研究降颅压效果与甘露醇用量以及其他影响因素的关系。方法选择60例颅内高压患者,应用NIP-200型无创颅内压监测仪监测患者每日颅压,计算最高颅压与最低颅压间的差值(降颅压效果),采用多元逐步回归方法分析降颅压效果与性别,年龄,最高颅压时的心率、血压以及降至最低颅压时甘露醇总用量的关系。结果60例患者最低颅压平均值为(213·4±66·8)mmH2O(83·5~364·5mmH2O),患者的颅压水平从入院至最低值时甘露醇总用量的平均值为(1870·8±861·9)ml(375~4000ml)。降颅压效果与最高颅压时的血压(舒张压和收缩压)和心率无相关性(P>0·05),与性别、年龄显著相关(P<0·05),与甘露醇用量显著相关(P<0·01)。结论甘露醇有明显的降颅压作用,但是用到一定的剂量后,便不再有降颅压作用。女性患者比男性患者降颅压的效果好。患者年龄越小,降颅压效果越好。     

基于GMDH型神经网络的EEG分类研究

为了提高对不同认知状态下脑电信号(EEG)的分类正确率，提出一种GMDH型神经网络及改进的训练算法。此网络结构在演化中生成，分类规则由简单多项式表示，训练算法可防止出现过拟合。此网络用于区分算术运算和休息状态下的脑电信号，正确率达到84．5％，与标准前向型神经网络(FNN)比较，显示了较好的分类效果。